Mineral wool panel comprising a web which covers both faces thereof

ABSTRACT

The invention relates to a mineral wool panel of increased structural strength, of the type of those used for the manufacture of air ducts, particularly airconditioning ducts, which are composed of a central core made of mineral wool, especially glass wool, coated on both faces with coatings, said core incorporating a web on the face located on the inside of the duct obtained, the panel of the invention being characterized in that it comprises a core ( 1 ) the surface faces of which, both the inner face and the outer face, each incorporate a respective web ( 2 ) extending over the totality of said faces, the two webs ( 2 ) being bonded to the surfaces of the core ( 1 ) by means of binders that can cure through the action of heat.

FIELD OF THE INVENTION

The invention relates to the field of insulating materials based on mineral wool and more particularly to materials intended for the manufacture of self-supporting ducts for distribution of air for ventilation or airconditioning.

SUBJECT OF THE INVENTION

The present invention relates to a mineral wool panel provided with a web covering both faces, which confers essential innovative characteristics and appreciable advantages over known means used for similar purposes in the prior art.

The invention proposes more particularly the development of panels made of mineral wool, preferably, but not exclusively, glass wool, of the type of those used for the manufacture of self-supporting ducts for distributing conditioned air, which panels are provided with a web covering both faces, said web being prepared for subsequently receiving, by adhesion, any other coatings intended for the panel, in which said web covering both faces provides a substantial uniform increase in the structural strength of the panel obtained, consequently improving the behavior of the duct into which it is incorporated as regards both positive and negative pressures.

The field of application of the invention lies, of course, within the industrial sector devoted to the manufacture of components for air, especially conditioned air, ducting installations.

BACKGROUND AND SUMMARY OF THE INVENTION

As known from the prior art, the manufacture of self-supporting ducts for the distribution of conditioned air using mineral wool, especially glass wool, panels, is a common and widely used practice.

The Spanish RITE (Regulations for Thermal Installations in Buildings) regulation deals, in the ITE 04.4 section, with self-supporting air distribution ducts produced from sheet metal and glass wool.

Mineral wool panels, generally made of glass wool, for the construction of ducts consist of a mineral wool core, comprising glass-derived fibers agglomerated with thermosetting binders, which is coated on one of its two faces (the edges of the panel not necessarily being coated). It should be explained that the term “faces” of the panel means here the principal faces of larger extent.

Generally speaking, the coatings used in these panels are the following:

a) Inner face of the duct: Normally, this surface is coated with an assembly called a “complex” formed from an aluminum film and kraft paper, which are bonded together, their arrangement and their composition or the order of the layers being capable of variation. In certain known products available on the market, a glass web (a nonwoven glass fiber fabric) is incorporated with the core of the panel, during manufacture of the latter, on the face designed to be on the inside of the duct, which web is consequently coated with said complex. Also on the market are products, used less and less, in which the inner surface coating consists only of said web, with no additional coating complex.

The function of all these various forms of coating is to prevent the fibers from being torn off by the circulation of air in the duct.

b) Outer face of the duct: This surface is, again, coated with a metal layer or with an assembly called a “complex” formed from a layer of aluminum, kraft paper and a glass fiber mesh (the arrangement and the composition or the order of the layers are capable of variation).

In fact, panels of this type are known in which the core may incorporate a glass fiber web only on one of its faces, said face always being placed in the part corresponding to the internal surface of the duct, once the latter has been formed. This web may remain uncovered inside the duct, or it may be provided with a coating.

At the present time, panels incorporating a web of glass fibers on the mineral wool core or organic polymer fibers on the external face, so that the outer complex or coating can adhere directly to the latter, are not known in the market.

Glass wool panels for the construction of ducts are cut up and assembled in order to create networks of air distribution ducts.

In practice, the air inside the ducts formed by these panels is conveyed at a predetermined static and dynamic pressure. Consequently, owing to the pressure exerted by the air inside the duct, the latter must possess a predetermined strength so as to prevent it from deforming and to avoid the resulting deterioration. With a view to ensuring that there is no deformation, the panels from which the ducts are constructed must have a certain flexural strength, independently of the reinforcing elements that may be placed along the duct.

The use of these panels in the specific application of the manufacture of ducts requires this flexural strength, or resistance to deformation, to apply both for positive pressures (expansion of the duct) and negative pressures (contraction or reduction in the internal cross section of the duct). In fact, the panel must exhibit flexural strength in both directions.

As is known, the strength of a duct of this type may be determined as a function of the Young's modulus and the moment of inertia of the panel. Likewise, the flexural strength of a panel may be determined from its deformation when it is under its own weight or when loaded.

The desired level of strength is generally obtained by improvements made to the core of the panel (which normally consists of mineral wool, generally glass wool, and synthetic resins that agglomerate it). These improvements consists in treating, or improving, the type of glass fiber and the binder that unites them, and also in increasing the density of the assembly formed by these components of the panel's core, among other things.

Even though the various coating layers applied to the core of the panel are in theory beneficial for strengthening the panel, the increase in strength is not significant, or at the very least is insufficient in practice to give the panel a higher strength class, because of its uneven behavior that depends on the way in which the pressure is exerted on the inside of the duct.

The main object of the present invention was to propose a mineral wool, preferably glass wool, panel that possesses substantially improved structural strength characteristics. This object was fully achieved by means of the mineral wool panel forming the subject of the following description, the main features of which are indicated in the preamble of claim 1.

The present invention essentially proposes the formation of a panel that is fundamentally distinguished from other known panels of the same type in that the panel of the invention has the particular feature of being coated with a web on both faces of the core that incorporates it.

It seems in fact that, for a panel incorporating a single web for the coating on the inside, the strength is not uniform owing to the fact that the web is present only on a single face of the duct.

The desired increase in the structural strength of the panel is obtained according to the invention thanks to the increase in the surface strength and in the tensile strength conferred by the web on both faces, thereby making it possible to obtain ducts with greater resistance both to positive pressures and to negative pressures (pulse and return or suction ducts).

According to the invention, the web is placed on each of the faces or surfaces of the panel's core and may be based on glass fibers or organic polymer fibers, or may comprise mixtures of polyester fibers and glass fibers, which are woven together, or are nonwoven and bonded together by means of a synthetic binder or a synthetic resin, and may also incorporate, optionally, a reinforcement formed from yarns. In this way, a highly reinforced panel of greater structural strength is obtained, the behavior of which with respect to positive or negative pressures is substantially improved when it is used in the construction of ducts for airconditioning installations.

The subject of the invention is also a method for increasing the strength of a mineral wool panel of the type of those used for the manufacture of air ducts.

BRIEF DESCRIPTION OF THE DRAWINGS

These features and advantages of the invention, and also others, will become more clearly apparent from the detailed description that follows of a preferred embodiment, given solely by way of illustrative example but implying no limitation, and with reference to the appended drawings in which:

FIG. 1 shows a schematic perspective representation of a portion of a mineral wool panel constructed according to the teachings of the present invention.

DESCRIPTION OF A PREFERRED EMBODIMENT

As indicated above, the detailed description of the preferred embodiment of the panel of the invention will be given below with the aid of the appended drawing. In this context, the single figure shows a schematic representation of a perspective view of the panel of the invention, which shows a mineral wool core 1, the inner and outer surfaces of which can receive, according to the invention, a web 2 on both of them, this being fastened to said surfaces, said webs extending over the totality of said respective surfaces, it being possible for the desired coatings 3, 4 to be applied to the outer face.

Each of the webs 2 incorporated on the inner and outer surfaces of the core of the panel consists of a multiplicity of glass fibers or organic polymer fibers, which are woven or nonwoven. The materials for manufacturing said webs 2 may also advantageously comprise a mixture of polymer (especially polyester) fibers and glass fibers.

By way of illustration, the grammage of a web that is useful according to the invention may be around 30 to 50 g/m², preferably 35 to 40 g/m².

When they are glass fibers, these may be mineral wool fibers, which are obtained by the attenuation in a gas stream of glass filaments, or chopped textile glass strands.

In general, the webs, in particular nonwoven webs, may comprise fibers bonded together by means of a synthetic binder or a synthetic resin.

The fibers making up the webs, whether woven or nonwoven, may comprise reinforcing yarns that may be natural or synthetic yarns, especially polymer yarns, or glass strands obtained by the attenuation/winding of glass filaments.

The webs 2 are fixed to the mineral wool (preferably glass wool) core 1 during the actual process for producing the latter, prior to the passage of the synthetic binders through the curing oven, which binders are used to mix with the glass fibers of the mineral wool. The adhesion of the webs 2 to the core 1 normally takes place using the same type of synthetic binder that agglomerates the fibers making up the mineral wool. In this way, the mineral wool, including the synthetic binder that is not yet cured, is placed between two surfaces of the web of the type described, in the manner of a sandwich. Said mineral wool sandwich, comprising a web 2 on each side, is introduced into the oven, in which the binder cures under the action of heat, so as to join the parts of this sandwich together and thus form an assembly taking the form of a rigid panel. This method of incorporating the webs 2 with the mineral wool core 1 ensures that said elements are intimately joined together, offering the advantage of increasing the strength of the core 1, which is much greater than that which the same webs would provide if they had been bonded differently.

Consequently, the panel of the invention is finally configured in the following order starting from the innermost face in contact with the air flowing in the duct manufactured from these panels:

-   -   Inner coating 3: this is formed from a complex multilayer, the         most conventional, but not exclusive, configuration of which         includes the incorporation of a film of aluminum and kraft         paper;     -   Core 1 of the panel: this consists of a body formed from mineral         wool, especially glass wool, of given density, on the outer and         outer faces of which is incorporated a web 2 based on glass         fibers or organic polymer fibers, or based on a combination of         both; and     -   Outer coating 4: this is formed from a multilayer complex, the         most conventional, but not exclusive, configuration of which         includes the use of a film of aluminum, a glass strand mesh and         kraft paper.

The composition of the panel, as proposed by the invention, makes it possible to achieve improvements affecting, in particular, the properties required of this type of panel in view of its use in the construction of airconditioning ducts, especially as regards its flexural strength. This increase in strength offers two fundamental advantages, namely the resistance to expansion or deformation of the duct manufactured from the improved panels, and the flexural strength of large panels (with a length of around 3 meters and a thickness of 2.5 cm), during the handling and transport before the mass production of the ducts. The reduction in the risk of bending into two of the panels, which prevents the use of the panel in the bending region (waste of material), also constitutes an important advantage both from the standpoint of handling and of installation costs.

Moreover, owing to the fact that usually, in order to increase the stiffness of the panel, it is normal practice to increase the density of the core 1 of the panel or its content of synthetic binders, the incorporation of the web 2 on both faces of the core 1 of the panels helps to reduce these criteria so as nevertheless to obtain the same results, or even greater efficiency. This reduction in the density may reach percentage values exceeding 5%, or, as a variant, it is possible to reduce the binder content with reductions of more than 2% points relative to the value used in equivalent panels that do not incorporate the proposed improvements (for example, on going from a binder content of 12% to a content of less than 10%). These reductions result in the costs of the production process being lowered. Thus, if we compare two panels, namely a first panel of conventional type not incorporating a web on both faces, and a second panel constructed according to the invention, in other words one provided with a web on both faces, the result obtained is that, for the same structural strength, the panel of the invention has a density of about 95% of the density of the first panel.

The table below presents the results of deflection measurements according to the EN 13403 standard on a panel according to the invention and, for comparison, on a panel with no webs. An equivalent level of strength is observed, with a considerably reduced density according to the invention. Example According to the invention Comparative Number of webs 2 0 Density (kg/m³) 72 82 Deflection (mm) 19 20

Moreover, the fact of incorporating, according to the invention, the web 2 on the outer face of the core 1 of the panel also makes it possible to increase the puncture resistance of the panel, once the latter has been coated on this face. This advantage may be used to reduce the coatings or complexes 3, 4 that are subsequently made to adhere to the core 1, insofar as the stresses to which they are subjected will be lower owing to the contribution of the web 2 to the mechanical strength of the whole assembly. Part of the reductions that can be applied to these complexes therefore affect the grammage of the organic components that they contain, which results in an improvement in the fire behavior of the outer coating and of the product in its entirety.

According to the invention, in the case where the web 2 is used on the outer face of the core 1 of the panel, a smoother surface is obtained, making it possible thereafter for the coatings (complexes) to adhere thereto using less adhesive or glue, hence an improvement in the behavior of the product and of the coating in a fire, and this being so for tests on said characteristic that are carried out in independent laboratories.

It would seem unnecessary to extend the content of the present description in order to allow an expert in the field to understand its scope and the advantages derived from the invention, and to develop and to put into practice its subject matter.

This said, it should be clearly understood that the invention has been described according to a preferred embodiment thereof, in such a way that modifications may be made thereto without in any way undermining the basis of said invention, these modifications possibly being made in particular to the shape, the dimensions or even the materials for manufacturing the assembly or its constituent parts. 

1. A mineral wool panel of increased structural strength, of the type of those used for the manufacture of air ducts, particularly airconditioning ducts, which are composed of a central core made of mineral wool, especially glass wool, coated on both faces with coatings, said core incorporating a web on the face located on the inside of the duct obtained, the panel of the invention being characterized in that it comprises a core (1) the surface faces of which, both the inner face and the outer face, each incorporate a respective web (2) extending over the totality of said faces, the two webs (2) being bonded to the surfaces of the core (1) by means of binders that can cure through the action of heat.
 2. The mineral wool panel as claimed in claim 1, characterized in that said web (2) covering each face of the core (1) is composed of glass fibers or organic polymer fibers, these being bonded together by means of a synthetic binder or a synthetic resin, or, where appropriate, of a mixture of polymer fibers and glass fibers.
 3. The mineral wool panel as claimed in claim 2, characterized in that the fibers making up the webs (2) comprise woven and/or nonwoven fibers.
 4. The mineral wool panel as claimed in either of claims 2 and 3, characterized in that the fibers making up the woven or nonwoven webs (2) include reinforcing yarns.
 5. The mineral wool panel as claimed in one or more of the preceding claims, characterized by a reduction in density of more than 5% compared to a conventional panel of identical structural strength.
 6. The mineral wool panel as claimed in one or more of the preceding claims, characterized by an increased resistance to expansion or to deformation of the air duct and also by a substantial increase in the puncture resistance compared to the panels coated on only one face.
 7. A method for increasing the strength of a mineral wool panel, of the type of those used for the manufacture of air ducts, especially airconditioning ducts, composed of a central core made of mineral wool, especially glass wool, coated on both faces with coatings, which comprises a step consisting in incorporating into the core, on each of its faces, a web that extends over the totality of said faces, the two webs (2) being bonded to the surfaces of the core (1) by means of binders that can be cured through the action of heat. 